Merge bitcoin/bitcoin#29186: ci, iwyu: Drop backported mappings

a395218 ci, iwyu: Drop backported mappings (Hennadii Stepanov)

Pull request description:

  See include-what-you-use/include-what-you-use#1026.

  Split from bitcoin/bitcoin#27710 as a non-controversial change.

ACKs for top commit:
  fanquake:
    ACK a395218

Tree-SHA512: ae7955a99396ab4f62ab7c989dba59c26448837f0ba4436bf3fddebe4099b5d3c03492e22a8497104c6afcceede1bb1b81f9d71c7c7e43692e6d70dcdfc11e7c

contrib/devtools/iwyu/bitcoin.core.imp

@@ -1,7 +1,4 @@
 # Fixups / upstreamed changes
 [
-  { include: [ "<bits/termios-c_lflag.h>", private, "<termios.h>", public ] },
-  { include: [ "<bits/termios-struct.h>", private, "<termios.h>", public ] },
-  { include: [ "<bits/termios-tcflow.h>", private, "<termios.h>", public ] },
   { include: [ "<bits/chrono.h>", private, "<chrono>", public ] },
 ]